Ha! The Onion Rings! I've read a lot of bashing against the poor cheap Tamron in this forum for that very reason. I would lilke to know what those people have to say now.
I'd really like to know how many people who'd never gotten the Tamron because of the horrible onion rings now will say that it's actually not that bad, that a zoom can never be a prime and the problem occurs only in specific shots :->
Kinda glad I didn't preorder one.
The mk2 may be more worthwhile on a high mp camera due to increased sharpness, and for heavy-duty event photogs that need the fastest af and more durability (which the mk2 has over the mk1 due to lensrentals).
For the rest of us, Canon should be renamed as the "$500 too much company" (5d3, 6d, 24-70ii) :-o
EDIT: removed mixup